Excimer light source

ABSTRACT

A light source, with electrodes of alternating polarity attached to a substrate in an excimer ultraviolet (UV) lamp, for generating a plasma discharge between each of the electrodes. The shape of the substrate can shape and control the plasma discharge to reduce exposure of materials susceptible to attack by the halogens. The electrodes can be located such that the plasma discharge occurs in a region where it produces less contact of the halogens with the vulnerable areas of the lamp enclosure. The materials, such as the electrodes, substrate, and envelope, can be selected to withstand corrosive materials. In another embodiment, a plurality of sealed tubes, at least some of which contain an excimer gas are positioned between two electrodes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to gas discharge light sources.

2. Description of the Related Art

Volatile organic compounds and other organic chemicals are widely usedas solvents, degreasers, coolants, gasoline additives, and raw materialsfor other synthetic organic chemicals. These organic compounds arecommonly found as trace contaminants in municipal and natural waterstreams. As a group, they are referred to as total oxidizable carbons(TOC). These compounds are very difficult to remove by conventionalmeans, such as filtration and absorption by media such as activatedcarbon.

Exposure to ultraviolet light (UV) is a means of removing TOC from waterin ultra-pure water systems. The ultraviolet light for TOC removal incurrent commercially available systems is produced by low-pressuremercury vapor lamps operating at the 185 nm wavelength. There also existsystems using pulsed light sources that produce broad spectrum lightbelow 250 nm. These pulsed light sources are typically xenon flashlamps.Excited dimer (“excimer”) pulsed discharge lamps have also been proposedfor removing TOC. Continuous discharge excimer light sources have alsobeen proposed. Examples of these devices are disclosed in U.S. Pat. No.7,439,663 to Cooper et al., which is incorporated herein by reference.

Excimer light sources to date use noble gas excimers (e.g., Xe₂*, Kr₂*,etc.) almost exclusively. The wavelengths of light which can begenerated by noble gas excimers is limited, and noble gas-halogenexcimers (e.g., ArF, KrCl, etc.) can generate light at some very usefulwavelengths not achievable with noble gas excimers. The reason thatnoble gas-halogen excimers are only used in a very few applications isdue in part to the fact that the halogen gases (e.g., F₂, Cl₂) that areused to form these excimers are highly reactive and chemically attackmost materials used in these devices. This impedes the operation of thelight source and ultimately damages it beyond repair, usually before apractical operating life time is achieved.

SUMMARY OF THE INVENTION

The system, method, and devices of the present invention each haveseveral aspects, no single one of which is solely responsible for itsdesirable attributes. Without limiting the scope of this invention, itsmore prominent features will now be discussed briefly. After consideringthis discussion, and particularly after reading the section entitled“Detailed Description of the Invention” one will understand how thefeatures of this invention provide advantages which include more costeffective water treatment.

In one embodiment, the invention comprises an ultraviolet (UV) excimerlamp comprising an envelope, an excimer gas, at least one firstelongated electrode extending at least part way along the length of theenvelope, and at least one second elongated electrode extending at leastpart way along the length of the envelope, and substantially parallel tosaid at least one first elongated electrode. The UV excimer lamp maycomprise a substrate to which the at least one first and secondelongated electrodes are attached, where the support is preferablyformed of a material or materials that reflect or transmit UV light. Theexcimer gas in the UV excimer lamp may advantageously comprise argonfluoride.

In another embodiment, a system for treating a fluid is provided. Thesystem may comprise a treatment chamber coupled to a fluid inlet and afluid outlet and at least one excimer gas discharge light source whereinthe light source is configured to expose a fluid passing through thetreatment chamber to radiation. In this embodiment, each light sourcecomprises an envelope, an excimer gas, at least one first elongatedelectrode extending along the length of the envelope, and at least onesecond elongated electrode extending along the length of the envelope,and substantially parallel to the at least one first elongatedelectrode.

Methods for purifying fluids are also provided. Such methods maycomprise producing light using an excimer gas discharge light source,the light having wavelengths in the range of 100 nm-400 nm and exposinga fluid to the light. The excimer gas discharge light source used toproduce the light comprises an envelope, an excimer gas, at least onefirst elongated electrode extending along the length of the envelope,and at least one second elongated electrode extending along the lengthof the envelope, and substantially parallel to the at least one firstelongated electrode.

In another embodiment, a UV excimer lamp comprises at least twoelectrodes and a plurality of sealed tubes, at least some of whichcontain an excimer gas therein, the plurality of tubes positioned atleast in part between the at least two electrodes.

Such a lamp may be used in a system, wherein a system for treating afluid comprises a treatment chamber coupled to a fluid inlet and a fluidoutlet and at least one excimer gas discharge light source wherein thelight source is configured to expose a fluid passing through thetreatment chamber to radiation. In this embodiment, the at least oneexcimer gas discharge light source comprises at least two electrodes anda plurality of sealed tubes, at least some of which contain an excimergas therein, the plurality of tubes positioned at least in part betweenthe at least two electrodes.

In addition, a method for purifying fluids of contaminants may compriseproducing light using an excimer gas discharge light source, the lighthaving wavelengths in the range of 100 nm-400 nm. In one embodiment, theexcimer gas discharge light source used to produce the light comprisesat least two electrodes and a plurality of sealed tubes, at least someof which contain an excimer gas therein, the plurality of tubespositioned at least in part between the at least two electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A depicts a system for creating a plasma discharge to generatelight, the system comprising an excimer lamp and a voltage source.

FIG. 1B depicts the internal construction of a cylindrical excimer lampwhich may be used in an embodiment of the system as depicted in FIG. 1A.

FIG. 2 illustrates two sets of six electrodes in accordance with severalembodiments of the invention.

FIG. 3 illustrates a linear design of two sets of three electrodes.

FIG. 4 illustrates two sets of six electrodes attached to a substrate.

FIG. 5 illustrates a linear design of two sets of three electrodes withsubstrate support.

FIG. 6 illustrates two sets of four electrodes attached to a substratewith cavities formed between the electrodes.

FIG. 7 illustrates two sets of four electrodes embedded in a substrate.

FIG. 8 illustrates electrodes embedded in inwardly extending portions ofa sealed envelope.

FIG. 9 illustrates another embodiment of a gas discharge light source,comprised of UV-transmissive cylinders filled with an excimer gas, withexternal electrodes producing an electrical discharge within thosecylinders.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following detailed description is directed to certain specificembodiments of the invention. However, the invention can be embodied ina multitude of different ways as defined and covered by the claims. Inthis description, reference is made to the drawings wherein like partsare designated with like numerals throughout.

Embodiments of the subject invention will extend the life of halogenatedexcimer lamps by any or all of the following: 1) limiting halogenexposure of materials susceptible to attack by the halogens, 2) locatingthe discharge in a region where it produces less contact between thehalogens and the vulnerable areas of the lamp, 3) selecting materialswhich can withstand immersion in an atmosphere containing thesecorrosive materials, and 4) using a high frequency or pulsed AC voltagesource to allow the use of insulated electrodes and to minimizeacceleration of halogen ions into the electrodes.

The figures and description herein illustrate and describe structuresfor a light source, with elongated electrodes of alternating polaritywhich may be attached to a substrate in an excimer ultraviolet (UV)lamp, for generating a plasma discharge between the electrodes. Theconfiguration of the substrate can shape and control the plasmadischarge to limit exposure of materials susceptible to attack byhalogens. The electrodes can be located such that the plasma dischargeoccurs in a region where it produces less contact between the halogensand the vulnerable areas of the lamp enclosure. The materials, such asthe electrodes, support, and envelope, can also be selected to withstandcorrosive materials.

FIG. 1A depicts a system for generating a plasma discharge to generatelight, the system comprising a cylindrical excimer lamp 12 and a voltagesource. Two voltage sources are illustrated, an AC voltage source 14,and an alternative DC voltage source 16. Thus, an AC, DC, or pulsedvoltage source is connected to, and can drive, opposite ends of thelamp. As described further below, the AC and pulsed voltage sources candrive electrodes that are bare or insulated, whereas the DC voltagesource typically only drives bare electrodes.

FIG. 1B depicts the internal construction of a cylindrical excimer lampwhich may be used in an embodiment of the system as depicted in FIG. 1A.The lamp typically comprises an envelope that contains the gas, but thatenvelope is not shown for simplicity such that the electrodes in thelamp can be more easily seen. As shown, there are two sets of fourelectrodes connected to respective sides of the voltage source at eachend of the lamp. One set is denoted 20 a-20 d, and the other set isdenoted 22 a-22 d. Thus, each electrode in a set is attached to one sideof the voltage source via a first contact electrode 24 for electrodes 20a-20 d, and a second contact electrode 26 on the other side forelectrodes 22 a-22 d, and thus each electrode in a given set is tied tothe same voltage. The first set of electrodes are connected to one sideof the voltage source at their proximal ends and extend from that sidealong the length of the lamp. The first set of electrodes is notconnected to the other side of the voltage source at their distal ends.The second set of electrodes connected to other side of the voltagesource at their proximal ends extend from that side along the length ofthe lamp substantially in parallel with the first set of electrodes andare not connected to the other side of the voltage source (which isconnected to the first set) at their distal ends. This producesinterleaved parallel electrode pairs that have opposite polarity andthat can support a plasma discharge therebetween. In variousembodiments, the spacing between the electrodes is between about amicrometer and a few millimeters. The electrode shape may advantageouslybe such that the electric field is constant over most of the axialdistance and does not exceed this value by a large amount at anyposition, particularly at the unconnected end. An AC, DC, or pulsedvoltage can be applied between each pair of alternating polarityelectrodes to create a stable electrical discharge in the surroundinggas mixture. The gas pressure should be high enough to allow efficientexcimer generation, a three-body process. Preferentially it should notbe below 0.1 Torr, or above 5000 Ton, but can be as high as themechanical structure of the gas envelope allows. The discharge plasmaoccurs between each of the alternating polarity electrodes. Although theconnections between the wires and respective sides of the power supplyare advantageously made at opposite ends of the lamp, it would bepossible to have different polarity wires connected to separate powersupply outputs at the same side of the lamp as well.

In the embodiment of FIG. 1, the lamp is an elongated cylinder. Forexample, the lamp may in some embodiments be about 5 mm-50 mm indiameter and up to about six feet in length. Although not shown, achamber filled with water to be purified can surround the lamp. Thechamber can preferentially contain a UV transmissive sleeve whichisolates the lamp from direct contact with the water. The sleeve may bedesigned to allow the lamp to be easily removed for replacement. Thus,the principles described herein may be used to produce a discharge lampwith an advantageous physical configuration for purifying water.

Discharge lamps having the structure shown in FIG. 1 can contain avariety of excimer gases. For example, a xenon excimer lamp produces UVoutput at 172 nm. This wavelength penetrates about 0.1 mm (decreases inabout 0.1 mm to 1/e of its initial value) through water. Because theabsorbance of water drops dramatically between 175 and 200 nm, it can beadvantageous to use slightly longer wavelengths when using UV lamps topurify water. Halogen excimer gases can provide these wavelengths. Forexample, argon fluoride has a slightly longer wavelength (193 nm), whichis slightly less energetic, but decreases in about 10 cm to 1/e of itsinitial value, and therefore can penetrate water over a much largerdistance than Xe excimer radiation. However, the fluorine gas requiredto generate argon fluoride is very corrosive, and can attack andultimately destroy the lamp components. These effects are minimized byemploying the embodiments described below. Thus, the principlesdescribed herein can also be used to produce a halogen discharge UVlight source having advantageous wavelength output for purifying waterthat has a long lifetime. A variety of halogenated gases can be used inthe lamps described herein. In addition to argon fluoride with awavelength of 193 nm, the lamp may contain krypton fluoride at a 248 nmwavelength or krypton iodide at a 184 nm wavelength. Other possibilitiesinclude krypton chloride and argon chloride. It will be appreciated thatany halogenated gas or gas mixture can be used advantageously with thelamp designs described herein, which, depending on the gas, couldproduce output wavelength or wavelengths from, for example, about 170 nmto about 310 nm.

In FIGS. 2 through 8 seven different physical lamp layouts are describedalong with some options for materials for the components comprisingthose structures. Each of these structures can be contained in a UVtransmissive envelope, and the structures in FIGS. 2-8 are illustratedas being surrounded by a cylindrical UV transmissive envelope 30.

The spacing between the electrodes and the pressure of the fill gas 32in the lamps may be such that the pressure of the gas mixture multipliedby the smallest distance between the electrodes, or the smallestdistance between the two coated surfaces covering the electrodes is inthe range 0.1-5000 Torr-cm. Further, the spacing between the twoelectrodes, or the smallest distance between the two coated surfacescovering the electrodes is normally less than 1 mm in such amicrodischarge structure.

The envelope that surrounds the substrate and the electrodes may becylindrical, sealed, light transmissive, and made from or coated withone or more of the substrate materials such that the light transmissiveenvelope is resistant to the corrosive effects of the gas mixturecontained within.

FIG. 2 illustrates a cross section of a structure with an array of twosets of six electrodes with alternating voltage polarity, arranged in acircle, surrounded by a UV transmissive envelope, in accordance withseveral embodiments of the invention. One set of electrodes areconnected to one side of the voltage source and the other set ofelectrodes are connected to the other side of the voltage source. Forconvention, electrodes 36 designated by “x” represent one polarity,whereas the electrodes 38 designated by “o” represent the oppositepolarity. These two sets of electrodes have a potential differencebetween them, creating a plasma discharge between adjacent oppositepolarity electrodes.

The electrodes in FIG. 2 may be bare or insulated. Examples of bare andinsulated materials that resist halogen corrosion include: barerefractory metal, bare molybdenum, bare hafnium, bare hafniumcoated/plated metal, bare nickel plated metal, PTFE insulated electrode,MgF₂ insulated electrode, CaF₂ insulated electrode, Al₂O₃ insulatedelectrode and TiO₂ insulated electrode. They also may be made ofresistive material, such as carbon composites, or dielectric materialcoated with thin layers of corrosion resistant metal.

If the electrodes are bare, the electrode material or coating (e.g., theelectrode materials discussed above) may be selected that resistcorrosion by the gas mixture. In one embodiment, the electrodes arebare. Non-insulated electrodes can be used with AC, DC, or pulsedvoltage. If the electrodes are insulated, the discharge voltage isprovided from a pulsed or AC source. For AC or pulsed sources, a higherfrequency or a shorter pulse width provided to the electrodes canminimize the acceleration of halogen ions into the electrodes. In oneembodiment, the voltage source delivers voltage from below radiofrequencies to microwave frequencies (e.g., between about 20 kHz andabout 300 GHz). A high frequency AC voltage source (e.g., over 100 MHz)accelerates the free electrons in the plasma but does not appreciablyaccelerate the heavy halogen ions, such that these ions are notundesirably accelerated into structural elements of the lamp. Instead,the fluorine ions only slowly drift into the lamp structures, whichreduces the rate of corrosion in comparison to ions accelerated into thestructures. Corrosion is a problem because it breaks down essentialproperties of the structure, which react with the halogen atoms,depleting the halogen concentration and reducing the excimer lightoutput of the lamp. Thus, the lifetime of a lamp can be improved whenoperated at high frequency, because free electrons are accelerated to ahigh velocity by the field, but the heavy ions are not accelerated intothe lamp materials.

FIG. 3 illustrates a linear design structure of two sets of electrodes36, 38. Unlike the previous figures, which illustrate a circular arrayof electrodes, this figure shows a basic linear design structure.Although shown with a cylindrical envelope, a rectangular or sheetshaped envelope is suitable with this electrode arrangement.

The electrode arrangements may be physically supported by a substrate 40to improve practicability and durability. FIG. 4 shows one such optionfor supporting a circular arrangement of the electrodes. This figureillustrates two sets of six electrodes attached to a substrate 40. Thesubstrate can be made from a substantially UV transmissive or reflectivematerial that is also resistant to the corrosive effects of the gasmixture. The substrate can be halogen resistant and transmit or reflect(not absorb) UV light below 300 nm (and in particular, below 200 nm).Examples of substantially transmitting and reflecting materials that canbe used for a substrate include: magnesium fluoride (MgF₂), calciumfluoride, barium fluoride, lithium fluoride, PTFE, titanium dioxide(TiO₂), and/or alumina/sapphire (Al₂O₃).

The envelope 30 that surrounds the substrate 40 and the electrodes 36,38 may be cylindrical, or another arbitrary, closed shape, sealed, lighttransmissive, and made from or coated with one or more of the substratematerials such that the light transmissive envelope is resistant to thecorrosive effects of the gas mixture contained within.

FIG. 5 illustrates a linear design structure of two sets of electrodeswith substrate 40 support. The substrate 40 provides additional supportto the electrodes.

FIG. 6 illustrates two sets of four electrodes attached to a substrate40 with cavities formed between the electrodes. This figure illustratesa further refinement, where the substrate 40 is shaped to have grooves42 that form cavities between the electrode locations to shape andcontain the plasma discharge, as well as to minimize the contact of theplasma with the substrate material. Furthermore, there is very littleplasma discharge adjacent to the sealed, light transmissive envelope.This reduces the potential corrosion of the envelope due to thedischarge. The cavities can be shaped as needed to provide the bestperformance. As in the other figures, a voltage discharge is createdbetween the electrodes. In this figure, eight discharges are created,one discharge between each adjacent pair of electrodes.

FIG. 7 illustrates two sets of four electrodes embedded in a substrate40. In this alternative construction, the electrodes are embedded withinthe substrate, where the substrate either transmits or reflects (butdoes not appreciably absorb) the light generated by the plasmadischarge. Also, as described above, the substrate is configured suchthat a cavity 44 is created to shape and control the plasma discharge.The cavities 44 can also serve to minimize the contact of the plasmawith the envelope.

It is further possible for the substrate 40 and the envelope 30 to beformed as a single structure with the electrodes embedded therein. Inthese embodiments, an excimer gas filled central region 32 of a hollowsubstrate can form the discharge region. Such an embodiment isillustrated in FIG. 8. In this embodiment, the electrodes are embeddedin inwardly extending portions 48 of a hollow, sealed envelope. Theexcimer gas is present in the internal hollow cavity. Discharges aregenerated in the hollow cavity in the regions 50 between the inwardlyextending portions in which the electrodes are embedded.

In some advantageous embodiments, the envelope/substrate is made ofquartz. As shown in FIG. 8, the inner surface of this envelope/substratecan have a coating 54 with the transmissive substrate materialsdescribed above. The embodiment of FIG. 8 can be produced by placingeach electrode inside a small tube, and then arranging each of thesecoated electrodes around the inner surface of a larger tube. A heattreatment can then be used to fuse the small tubes to the inner surfaceof the larger tube. Prior to heat treatment, the small tubes could behelp in place with a central mold that has a higher thermal coefficientof expansion than the tube materials. The central mold can be slidinside the larger tube with the smaller tubes on the inner surfacethereof, and during the heat treatment, the central mold can expandagainst the smaller tubes, pressing them against the inner surface ofthe larger tube. After cooling, the central mold can be slid back out.Although a variety of materials may be used as the envelope in thisembodiment, quartz is advantageous. After the heat treatment, a coating54 of, for example, magnesium fluoride (MgF₂), calcium fluoride (CaF₂),barium fluoride (BaF₂), lithium fluoride (LiF), PTFE, titanium dioxide(TiO₂), and/or alumina/sapphire (Al₂O₃) may be provided on the innerssurface to enhance longevity depending on the excimer gas being used.This embodiment is advantageous due to its simple, essentially singlepiece construction.

FIG. 9 illustrates another embodiment an array of two or more tubes 60that are filled with an excimer discharge gas. The tubes 60 are shown ascylinders in this case, but could be of any arbitrary shape. The tubesare filled with the excimer gas, to the proper pressure, then sealed. Apulsed or AC voltage is then applied by electrodes 62 a and 62 b toproduce a transverse electric field across the tubes, which leads to anelectrical discharge inside the tubes. Two electrodes are shown, but itmay be advantageous to intersperse more electrodes in between theelements of the array of tubes to enhance breakdown performance. Theelectrodes 62 a, 62 b may be bare metal or may be covered with areflective and/or electrically insulating coating to prevent absorptionof the light generated inside the tubes and to ensure that there is lesslikelihood of electrical breakdown between the opposing electrodes. Theelectrodes need not fully encompass or surround the tubes, they needonly be of sufficient size and location with respect to the tubes to becapable of causing excimer discharge therein.

The transverse distance across the tube and the gas pressure inside thetubes are such that the pressure times distance product is in the range0.1-5000 Torr-cm for proper microdischarge operation. The tubesthemselves can be made from a variety of materials. In this embodiment,quartz is advantageous. The tubes may include a coating of, for example,magnesium fluoride (MgF₂), calcium fluoride (CaF₂), barium fluoride(BaF₂), lithium fluoride (LiF), PTFE, titanium dioxide (TiO₂), and/oralumina/sapphire (Al₂O₃), which may be provided on the inner surface ofthe tube to enhance longevity, depending on the excimer gas being used.Other embodiments may use one or more of these coating materials to formthe complete tubes, eliminating the need for a separate coating step.The entire assembly may or may not be contained within an outer, UVtransmissive envelope, shown alternatively as 64 and 66 for handlingprotection and/or gas or liquid cooling purposes. As shown by the twopossibly envelope configurations in FIG. 9, the electrodes in a devicewith an outer envelope can be either inside (e.g. with envelope 64) oroutside the envelope (e.g with envelope 66).

This embodiment can be advantageous because the sealed tubes can containonly or essentially only gas, with no electrodes or other functionalmaterials or components inside (other than the inside surface of thetube, which may be coated as described above) that come into contactwith and may be degraded by the excimer gas. This provides for a longlasting UV lamp with a simple and inexpensive construction.

While the above detailed description has shown, described, and pointedout novel features of the invention as applied to various embodiments,it will be understood that various omissions, substitutions, and changesin the form and details of the device or process illustrated may be madeby those skilled in the art without departing from the spirit of theinvention. For example, it may be advantageous to use the electrodes asballast resistors. If this is done, the lamp can be cooled by runningwater through one of more channels extending axially through the body ofthe substrate. The scope of the invention is indicated by the appendedclaims rather than by the foregoing description. All changes which comewithin the meaning and range of equivalency of the claims are to beembraced within their scope.

What is claimed is:
 1. An UV excimer lamp comprising: at least twoelectrodes; a plurality of sealed tubes, at least some of which containan excimer gas therein, the plurality of tubes positioned between the atleast two electrodes, wherein the at least two electrodes are notbetween any of the plurality of sealed tubes; and an envelope thatsurrounds the plurality of sealed tubes, wherein the at least twoelectrodes are outside of the envelope.
 2. The UV excimer lamp of claim1, wherein the excimer gas comprises a noble gas, a halogen, or amixture thereof.
 3. The UV excimer lamp of claim 2, wherein the excimergas comprises argon fluoride.
 4. The UV excimer lamp of claim 2, whereinthe excimer gas comprises krypton fluoride.
 5. The UV excimer lamp ofclaim 2, wherein the excimer gas comprises krypton chloride.
 6. The UVexcimer lamp of claim 1, wherein at least one of the at least twoelectrodes are insulated.
 7. The UV excimer lamp of claim 1 furthercomprising a voltage source connected across the at least twoelectrodes.
 8. The UV excimer lamp of claim 7, wherein the voltagesource comprises a pulsed voltage source.
 9. The UV excimer lamp ofclaim 8, wherein the pulse frequency is from about 20 kHz to about 300GHz.
 10. The UV excimer lamp of claim 7, wherein the voltage sourcecomprises an AC voltage source.
 11. The UV excimer lamp of claim 10,wherein the frequency of the AC voltage is from about 20 kHz to about300 GHz.
 12. The UV excimer lamp of claim 1, wherein the sealed tubesare formed of quartz.
 13. The UV excimer lamp of claim 1, wherein thesealed tubes are coated on an inside surface thereof.
 14. The UV excimerlamp of claim 13, wherein the coating comprises one or more of magnesiumfluoride (MgF2), calcium fluoride (CaF2), barium fluoride (BaF2),lithium fluoride (LiF), PTFE, titanium dioxide (TiO2), andalumina/sapphire (Al2O3).
 15. The UV excimer lamp of claim 1, whereinthe sealed tubes are formed of one or more of magnesium fluoride (MgF2),calcium fluoride (CaF2), barium fluoride (BaF2), lithium fluoride (LiF),PTFE, titanium dioxide (TiO2), and alumina/sapphire (Al2O3).
 16. The UVexcimer lamp of claim 1, wherein the sealed tubes contain essentiallyonly gas.
 17. A system for treating a fluid comprising: a treatmentchamber coupled to a fluid inlet and a fluid outlet; and at least oneexcimer gas discharge light source wherein the light source isconfigured to expose a fluid passing through the treatment chamber toradiation, wherein the at least one excimer gas discharge light sourcecomprises: at least two electrodes; and a plurality of sealed tubes, atleast some of which contain an excimer gas therein, the plurality ofsealed tubes positioned between the at least two electrodes, wherein theat least two electrodes are not between any of the plurality of sealedtubes, wherein the at least one excimer gas discharge light sourcefurther comprises an envelope that surrounds the plurality of sealedtubes, wherein the at least two electrodes are outside of the envelope.18. The system of claim 17, wherein said treatment chamber surrounds anenvelope.
 19. The system of claim 18, wherein the treatment chambercomprises a sleeve isolating the fluid from contact with the lightsource.
 20. The system of claim 17, wherein the excimer gas comprises anoble gas, a halogen or a mixture thereof.
 21. The system of claim 20,wherein the excimer gas comprises argon fluoride.
 22. The system ofclaim 20, wherein the excimer gas comprises krypton fluoride.
 23. Thesystem of claim 20, wherein the excimer gas comprises krypton chloride.24. The system of claim 17, wherein the sealed tubes contain essentiallyonly gas.
 25. A method for purifying fluids of contaminants comprising:producing light using an excimer gas discharge light source, the lighthaving wavelength in a range of 100 nm-400 nm; and exposing a fluid tothe light, wherein the excimer gas discharge light source used toproduce the light comprises: at least two electrodes; and a plurality ofsealed tubes, at least some of which contain an excimer gas therein, theplurality of sealed tubes positioned between the at least twoelectrodes, wherein the at least two electrodes are not between any ofthe plurality of sealed tubes, and wherein the excimer gas dischargelight source used to produce the light further comprises an envelopethat surrounds the plurality of sealed tubes, wherein the at least twoelectrodes are outside of the envelope.
 26. The method of claim 25,wherein the gas discharge light source produces light having awavelength between about 170 nm and 310 nm.
 27. The method of claim 26,wherein the gas discharge light source produces light having awavelength of about 193 nm.
 28. The method of claim 26, wherein the gasdischarge light source produces light having a wavelength of about 222nm.
 29. The method of claim 26, wherein the gas discharge light sourceproduces light having a wavelength of about 248 nm.
 30. The method ofclaim 25, wherein the fluid consists essentially of water.
 31. Themethod of claim 25, wherein the sealed tubes contain essentially onlygas.